Forest Product Laboratory
Informative government research site.
Articles such as:
Before Installing Exterior Wood-Based Siding
Finishes for wood Decks
Mold and Mildew On Wood: Causes and Treatments
Outdoor Furniture, Artwork, Fences, and Play Equipment
Painting & Finishing Fact sheets
What's in That Pressure-Treated Wood
Why House Paint Fails
Wood Deck Construction and Maintenance